I will pick my battles
My mentor in graduate school once said, "The key to marriage isn't true love. It isn't honesty or adventure or trust. The key to marriage is figuring out how to live with that person's glob of toothpaste in the sink, or their wet towels on the bathroom floor, for the rest of your life. When you can say, 'Yes, I hate that glob of toothpaste, but I can deal with it,' then you've figured out how to survive marriage."
Does it drive me up the wall that the floor on my husband's side of the bed is a gathering place for his shoes, gym clothes, headphones, and any other miscellaneous items he's too lazy to put away? Yes. Does it make me crazy when he wears sweats for dinner in the city while I'm in a dress and heels? Absolutely.
But those things just aren't worth a big fight. Whenever I get worked up over something petty, like if I'm late for work, my husband will stop me and say, "Is this going to matter 10 years from now?" It seems so simple, but qualifying things that way really does help me stop sweating the small stuff.